In this Phase I SBIR project Alderon Biosciences Inc. (ABI) proposes to demonstrate the feasibility of using electrochemical reverse transcriptase (eRT) assays for determinations of HIV viral load in clinical samples. Success will set the stage for Phase II development, FDA approval, and production of commercial kits using this advanced technology. The long-range goal is to produce an affordable (equal to or <$10) HIV viral load test that gives same-day results using an inexpensive and portable instrument. Currently available FDAapproved PCR-based tests for determination of HIV viral load require expensive instrumentation, utilize complex molecular biology procedures, and can cost $100-$250 per test. ABI's project goal is a response to the urgent need for a HIV viral load measurement system that is practical and affordable for use in resource-poor settings. ABI's lower-cost viral load assays could increase the effectiveness of antiretroviral therapy and decrease the incidence of virus transmission for millions of infected patients in resource-poor settings. The innovation in the new RT assays proposed by ABI lies in the use of advanced electrochemical detection methods for quantifying RT activity. RT assays are a recognized (but not FDA-approved) alternative method for viral load monitoring. Unlike PCR-based assays that have problems quantifying some HIV subtypes, RT activity tests work equally well for HIV-1 (regardless of subtype) and HIV-2 and are less subject to problems of contamination than PCR-based assays. Formation of an optically detectable product is a measure of RT concentration in commercially available RT-activity kits. In ABI's adaptation of the optical assays, RT activity will result in catalytic incorporation of many electroactive labels on extended chains at a sensor surface. An extremely low-cost potentiostat will apply a potential and amperometrically measure the amount of current catalyzed by the electroactive labels tethered to the sensor surface. The current generated in the eRT assays will reflect the amount of RT in the sample. Collaborative work with the UNC Center for AIDS Research will establish the correlation of the eRT assay results with plasma levels of HIV. The measurable milestone of Phase I work will be demonstration of accurate, quantitative and precise eRT measurements with significant correlation (r D 0.90) to PCR-based determinations of plasma HIV viral load and sensitivity down to 300 virus particles/mL.